Sandbags find use in many different situations. For example, sandbags may be used to hold back flood waters, to protect soldiers from bullets, artillery, etc. on the battlefield, and to protect structures such as buildings, camps, etc. from explosive devices.
While sandbag walls may provide a measure of protection in such circumstances, they also may have several drawbacks. For example, the construction of a sandbag wall may require a large number of people, and may take an excessive amount of time to fill the bags and arrange them into a barrier structure. Also, a sandbag wall may have points of weakness, as the individual sandbags are generally merely stacked upon one another, rather than being attached to one another. Furthermore, the sandbags are generally not reusable. Thus, they may require an expensive and time-consuming disposal process, and new ones may need to be purchased after each emergency event in anticipation of future emergency events.
Modular systems for forming temporary barrier structures are also known. For example, U.S. Pat. Nos. 4,785,604 and 4,945,689 to Johnson, Jr. disclose collapsible grid structures for forming temporary barriers. The grids are formed from a plurality of latitudinal and longitudinal strips connected in an interwoven fashion. The grids are configured to be connected to adjacent grids in both stacked and side-by-side manners, and then filled with a material such as sand to form the temporary barrier. The grids may allow a temporary barrier structure to be assembled more quickly and with less manpower than a comparable sandbag structure.
The grids disclosed in Johnson are joined in a side-by-side manner via connector slots formed in the ends of the latitudinal and the longitudinal strips. The connector slots extend into the strip from the either the top of the strip or from the bottom of the strip. To connect a grid to an adjacent grid, the grids are arranged side-by-side in such an orientation that the connector slots that extend from the top of the strips on the grid are aligned with complementary slots on the adjacent grid that extend from the bottom of the strips, and vice versa. The connector slots are then coupled with the complementary slots to join the grids.
While the grids disclosed in Johnson offer improvements over the use of traditional sandbags to form temporary barrier structures, they also may suffer some shortcomings. For example, the connector slots may be difficult to connect in inclement conditions, as it may be difficult to determine the correct grid orientation in which the connector slots line up with the correct complementary slots. Likewise, it may be difficult to determine whether complementary slot connectors are securely connected.
Additionally, the ends of the strips of the grids disclosed in the Johnson, Jr. patents may tend to dog-ear when the cells formed at the boundary between adjacent grids are filled with a fluent material due to the connector slots. This may prevent these cells from being entirely filled with fluent material, and thus may introduce a structural weakness into the barrier wall that may potentially cause catastrophic failure under extreme conditions. Another potential problem with the Johnson grid is that it may be difficult to stack a plurality of grids to form a wall under low visibility conditions and/or without undergoing training to learn how to spot and fix an incorrectly stacked wall. Additionally, the strips of the Johnson grid terminate in ninety degree corners that may impede the smooth movement of the grid between collapsed and deployed configurations.